1. Technical Field
The present invention relates to a liquid ejecting head unit that ejects liquid through nozzles and to a liquid ejecting apparatus including the liquid ejecting head unit. More specifically, the invention relates to an ink jet recording head unit that ejects ink as the liquid and an ink jet recording apparatus including the ink jet recording head unit.
2. Related Art
Ink jet recording head units that eject ink droplets are a representative example of liquid ejecting head units that eject liquid. For example, JP-A-2009-6730 proposes an ink jet recording head unit that includes an ink jet recording head and a flow path member. The ink jet recording head ejects ink droplets through the nozzles. The flow path member is fixed to the ink jet recording head and allows ink in a liquid storage unit that stores the ink, such as an ink cartridge, to be supplied to the ink jet recording head.
The flow path member in the ink jet recording head unit includes an upstream flow path member and a downstream flow path member that holds the ink jet recording head; the upstream and downstream flow path members allow the ink in the liquid storage unit to be supplied to the ink jet recording head. In addition, a seal member made of an elastic material, such as a rubber sheet, is interposed between the upstream and downstream flow path members in order to suppress the ink from leaking from the connecting parts of the upstream and downstream flow paths.
The above configuration in which the seal member between the upstream and downstream flow path members hermetically seals the connecting parts of the upstream and downstream flow paths has some disadvantages. More specifically, the seal member generates a repelling force in response to its elastic deformation, and this repelling force applies forces to the upstream and downstream flow path members in the directions in which the upstream and downstream flow path members are separated from each other. In addition, a force is applied vertically to the liquid ejection surface of the liquid ejecting head from which ink droplets are to be ejected. Consequently, the upstream and downstream flow path members may be separated from the liquid ejecting head, or stacked members constituting the liquid ejecting head may be separated from one another. Moreover, the liquid ejection surface of the liquid ejecting head may be warped, in which case locations at which ink droplets are to be placed on a medium, such as a paper sheet, might be displaced.
As another example, JP-A-2015-003421 proposes a configuration (first exemplary configuration) in which a first flow path is connected to a second flow path with a tube therebetween, which helps decrease a force applied vertically to a liquid ejection surface.
JP-A-2015-000542 proposes a configuration (second exemplary configuration) in which a first flow path is connected to a second flow path with a tubular seal member therebetween. This tubular seal member presses the first flow path in a radial direction and also presses the second flow path in a direction perpendicular to a liquid ejection surface.
The first exemplary configuration involves a complex assembly process in which the tubular seal member is inserted into the first and second flow paths while the first and second flow paths are aligned with one another. More specifically, when the seal member that has been inserted into the first flow path is inserted into the second flow path, a manufacturer may fail to visually check the connecting parts of the seal member and of the second flow path, in which case the first flow path might be misaligned with the second flow path and thus ink might leak from the connecting parts.
Although the second exemplary configuration can be assembled by a simple process, if the tubular seal member expands in response to application of pressure to the ink, the adhesion between the seal member and projecting parts formed in the first and second flow paths may decrease, in which case an ink leakage might occur between the seal member and the projecting parts.
The above disadvantages are common not only to ink jet recording head units but also to liquid ejecting head units that eject liquid other than ink.